Such a system is known, for example, from EP 457 246 B1. To transfer the bed onto the trolley, the latter is brought into a suitable position in relation to the support column. By means of the downward movement of the height adjustment device of the support column, the bed is first lowered, until it lies on the trolley. At the moment of transfer the first coupling elements on the bed are simultaneously in engagement with the second and third coupling elements on the column and on the trolley respectively.
In the patient bed system known from EP 457 246 B1, the coupling elements of the bed are assigned two spring-loaded locking bolts, of which one locking bolt latches in the coupling element of the column when the bed lies on the column and the other locking bolt latches in the coupling element of the trolley when the bed lies on the trolley. In the case of the take-over operation, for example from the trolley onto the column by means of an upward movement of the column, the locking bolt latched in the coupling element of the trolley is pressed back by a control contour of the column and consequently unlocks the bed on the trolley. At the same time, the presence of the trolley initially prevents the latching of the other locking bolt in the coupling element of the column. Only by the bed being lifted out of the trolley can the second locking bolt latch into the coupling element of the column under spring prestress at an increasing distance from the coupling element of the trolley. Conversely, the locking bolt latched in the coupling element of the column is pressed back by a control contour of the trolley, whilst the other locking bolt latches in the coupling element of the trolley under the action of the spring force at an increasing distance of the column from the bed. At the moment of take-over, that is to say when the coupling element of the column and the coupling element of the trolley are in engagement with the coupling element of the bed, the bed is not protected by any locking bolt against being lifted out. Moreover, situations may arise in which the locking bolts are prevented from snapping in under spring force, for example if the coupling elements are tilted slightly with respect to one another.